The invention relates generally to baskets for retrieving material in a body. More particularly, the invention relates to urology baskets having legs with a certain crosssection designed to retrieve kidney stones, urinary calculi, choleliths, or the like from within the body while causing less trauma to the body and enhancing stone capture.
Baskets are used to retrieve various foreign or biological materials (e.g., kidney stones, urinary calculi, choleliths, etc.) from within a body. Baskets are used in the field of urology and other areas such as, for example, endoscopy. Existing retrieval baskets typically include a plurality of wires (or legs) which truncate at a base of the basket. It is known to form the legs of the basket from wire having a rectangular cross-section (FIG. 5A) or a round cross-section (FIG. 5B). The legs are joined by solder, weld, or mechanical means at the base of the basket and at its distal tip. At the base, the legs also are attached to a shaft coil (or wire). This coil is moved back and forth within a sheath or catheter by an actuation device (e.g., a proximal handle with a back-and-forth thumb-activated slider). By moving the coil forward with the actuation device, the legs are extended out of the distal end of the catheter and thus allowed to expand and form the basket shape beyond the distal end of the catheter. Moving the coil back causes the basket to retract into the catheter.
In general, the advantages of basket legs having a rectangular cross-section include good dilatation force and good contact between the inner surface of the legs and the stone, and the disadvantages of such legs include sharp edges (i.e., the top two corners of the rectangle that contact the interior wall of the lumen in which the basket is disposed) and thus tissue trauma, inability to rotate the basket due to the danger of tissue trauma, and the difficulty of forming a helix-shaped basket structure when the basket is expanded. In general, the advantages and disadvantages of basket legs having a round (or circular) cross-section are the opposite of those encountered with legs of rectangular cross-section. That is, the advantages of legs of round or circular cross-section generally include round edges and thus reduced tissue trauma, ability to rotate the basket without danger of tissue trauma, and ability to form a helix-shaped basket structure, and the disadvantages of legs of round cross-section generally include less dilatation force and less contact between the inner surface of the legs and the stone being captured.
The invention relates to a medical retrieval basket having legs with a cross sectional shape designed to enhance the capture and retrieval of foreign materials or biological materials (e.g., kidney stones, urinary calculi, etc.) from within a body while causing less trauma to tissue. The two basic design objectives according to the invention are (1) to cause less trauma to body tissues and to the linings of lumens of the body in which the basket is placed and manipulated to accomplish the retrieval of material and (2) to enhance the material-capturing ability of the basket. One shape that meets the two basic design goals of the invention is a basket having legs with a D-shape in cross-section. Advantages of the D-shape, and all other shapes according to the invention, include less trauma to tissue, ability to rotate the basket without forming the legs in a helix configuration, improved stone purchase and contact, ability to use the basket for tissue biopsy because of its improved cutting ability, improved stone breaking and/or crushing ability, ability to reduce the overall size of the catheter basket device while maintaining or increasing the opening force of the basket, and improved dilatation force compared to a basket with legs of round cross-section while making the basket less tissue traumatic.
In accordance with the invention, a medical retrieval device, and related method, uses a basket formed by one or more legs to retrieve foreign or biological material. At least one of the legs has at least two surfaces, namely, an inner surface and an outer surface. The outer surface is an atraumatic surface such as a curved surface. The atraumatic outer surface can include one or more radii. The inner surface can be flat such that the leg has a D-shaped cross section. Other shapes are possible for the inner surface including a pointed shape that enhances the basket""s stone crushing or breaking ability. The inner surface, whatever its shape, can have a smooth surface, or it can have a rough surface (e.g., serrated, etched, toothed, etc.) for further enhancing the basket""s ability to capture material such as stones and other calculi.
In one aspect, the invention involves a medical retrieval device. The device comprises a basket that includes one or more legs that form the basket. At least one of the legs comprises at least two surfaces wherein at least one of the two surfaces comprises a curved surface.
Embodiments of this aspect of the invention can include the following features. For example, the leg with the at least two surfaces can have a cross section defined by the surfaces, and the cross section can comprise a D-shape defined by the surfaces wherein the curved surface comprises an outer surface and the other surface comprises an inner surface. In general, the curved surface can comprise an outer surface and the other surface can comprise an inner surface. The inner surface can comprise a flat surface such that the cross section comprises a D-shape, or the inner surface can be wedge-shaped and comprise at least one point. Also, the inner surface can comprise a surface that is rougher than the outer surface, and this rough inner surface can comprise, for example, a serrated surface, a toothed surface, or an etched surface. The curved surface can comprise more than one radius (e.g., a B-shape). The basket can have three or more legs.
In another aspect, the invention relates to a medical retrieval device that comprises a basket having one or more legs forming the basket. At least one of the legs comprises at least an inner surface and an outer surface wherein the outer surface comprises an atraumatic surface.
Embodiments of this aspect of the invention can include a curved surface as the outer atraumatic surface. Other embodiments of this aspect of the invention can include other features such as those described above for the previous aspect of the invention.
In still another aspect, the invention involves a method for retrieving material from a body. The method comprises inserting an extractor into a body. The extractor comprises a basket having one or more legs forming the basket, and at least one of the legs comprises at least an inner surface and an outer surface wherein the outer surface comprises an atraumatic surface. The method further comprises capturing the material with the basket. The captured material contacts the inner surface of at least one of the legs. The method further comprises withdrawing the extractor from the body to remove the captured material from the body.
Embodiments of this aspect of the invention can include the following features. For example, the capturing step can comprise capturing a calculus such as, for example, a kidney stone, a ureteral stone, a urethral stone, a urinary bladder stone, or a stone in the biliary tree such as a gallbladder stone or a bile duct stone. Also, the capturing step can further comprise breaking the material into two or more pieces with, for example, a sharpened inner surface.
In yet another aspect, the invention relates to a medical retrieval device that comprises a basket having one or more legs that form the basket. At least one of the legs comprises at least an inner surface, and at least a portion of the inner surface is adapted to contact material (e.g., calculi) and is rough. The rough inner surface can be, for example, a serrated surface, a toothed surface, or an etched surface.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.